1. Field of the Invention
The present invention relates to a slider used for a floating magnetic head and so on.
2. Description of the Related Art
A floating magnetic head used for a magnetic disk unit and so on is generally made up of a thin film magnetic head element formed at the trailing end of a slider. The slider generally comprises a rail whose surface functions as a surface facing a medium (referred to as medium facing surface in the following description) or an air bearing surface and a tapered section or a step near the end on the air inflow side. The rail floats slightly above the surface of a recording medium such as a magnetic disk by means of air flow from the tapered section or step.
As disclosed in Japanese Patent Laid-open No. 6-282831 (1994), for example, such a slider requires a process for curving (rounding) edges of the rail between the medium facing surface and the outer side of the rail so that the edges will not scratch a recording medium when the slider is swung and tilted. For the slider disclosed in Japanese Patent Laid-open No. 6-282831, the outer sides of two rails are the sides of the slider.
Sliders for magnetic heads are formed through cutting a wafer in one direction on which a number of magnetic head elements are formed in a matrix for forming blocks called bars each including a plurality of magnetic head elements in a row. Rails are then formed for each bar and the bar is cut into sliders. For the slider disclosed in Japanese Patent Laid-open No. 6-282831 mentioned above, the outer sides of two rails are the sides of the slider. However, a slider with such a shape may have chippings in the rails due to machining for cutting the bar into sliders.
Therefore a slider as shown in FIG. 24 is generally known where rails 113 are formed so that sides 114 of the rails 113 are located inside sides 112 of the slider 111, that is, the cutting plane of the bar, by a given distance. A slider with such a structure will be called a two-level slider in the following description.
Processing also is performed on such a two-level slider for curving (rounding) edges of rails. As disclosed in Japanese Patent Laid-open No. 6-12645 (1994), for example, methods known for removing edges of rails include oscillating the slider on a lapping film with diamonds placed on an elastic substrate. FIG. 25 is a schematic view for illustrating this method. In the method a plurality of sliders 111 fixed to a jig 115 are pressed in the direction shown with an arrow 118 against a diamond lapping film 117 placed on a plate-shaped elastic substrate 116 made of silicone rubber, for example. While pressed against the lapping film 117, the sliders 111 are oscillated in two lateral directions for removing edges 119 of rails 113.
FIG. 26 is a magnified view of the neighborhood of the edges 119 of the rails 113 (section A in FIG. 25) having being processed in the method shown in FIG. 25.
As disclosed in Japanese Patent Laid-open No. 2-301014 (1990), another processing method is known for oscillating a lapping tape against rails of sliders while the lapping tape is reciprocated with a guide.
A reduction in amount of floatation has been desired for improving recording densities. An improvement in floatation stability has been desired as well for higher access speed. For meeting these demands a negative pressure slider has been used. In general the negative pressure slider has a recess between two rails for generating negative pressure. Such a negative pressure slider has a minute structure on the surface facing a recording medium. In particular the height of the rail is much lower than that of other types of sliders.
As shown in FIG. 27, such a negative pressure slider with a low rail height may scratch a recording medium. When a slider 121 is tilted, edges 124 between sides 122 of the slider 121 and a surface 123 of the slider 121 facing a recording medium 125 and orthogonal to the sides 122 may touch and scratch the recording medium 125. This problem is particularly noticeable in a hard disk drive used in a portable apparatus such as a notebook personal computer in which a slider often 15 tilted.
The slider 121 may be tilted in various manners. As shown in FIG. 27, the slider 121 may be tilted with one side thereof positioned lower than the other side. Furthermore, as shown in FIG. 28A, the slider 121 may be tilted with an end 131 on the air inflow side of the slider 121 positioned lower than an end 132 on the air outflow side. As shown in FIG. 28B, the slider 121 may be tilted with the end 132 on the air outflow side of the slider 121 positioned lower than the end 131 on the air inflow side. As shown in FIG. 29A, the slider 121 may be tilted with one side of the end 131 on the air inflow side of the slider 121 positioned lower than the other side of the end 132 on the air outflow side. As shown in FIG. 29B, the slider 121 may be tilted with one side of the end 132 on the air outflow side of the slider 121 positioned lower than the other side of the end 131 on the air inflow side.